In recent years, in optical components used for products such as a display and a lighting device, it is desirable to realize a device having the expression of an unprecedented new function which controls reflection and diffraction of light by forming a fine pattern in nanometer (nm) order to micron (μm) order exerting particular optical characteristics. As methods for forming the fine pattern, an imprinting technique is attracting attention recently in addition to a photolithography technique and an electron beam lithography technique.
The imprinting technique is a method of forming the fine pattern of a mold by pressing the mold in which the fine pattern is previously processed on the surface onto a resin applied to a substrate surface.
As imprinting methods, there are a thermal imprinting method in which the mold heated to be higher than a glass transition temperature is pressed onto a thermoplastic resin applied to the substrate surface to thereby transfer the fine pattern and a UV imprinting method in which a UV curing resin is used and irradiated with a UV light while pressing the mold to thereby transfer the fine pattern.
Although the thermal imprinting method has a feature in which the selectivity in the material is wide, there is a problem that the throughput is low as it is necessary to increase and decrease the temperature of the mold at the time of transferring the fine pattern. On the other hand, in the UV imprinting method, the selectivity in the material is narrower than that of the thermal imprinting method as materials are limited to materials to be cured by ultraviolet rays. However, there is an advantage that the throughput is extremely high as the curing can be completed for several seconds to several tens of seconds. Which of the thermal imprinting method and the UV imprinting method is adopted depends on devices to which the method is applied. The UV imprinting method is considered to be suitable for the mass production method when there is no problem caused by the material.
(Imprinting Technique)
A common process flow for forming a fine pattern by the UV imprinting method will be explained. FIG. 13 show schematic diagrams of a common flat-plate imprinting process. First, a UV curing resin 12 is applied to the entire surface of a substrate 11 by using a spin-coating method and so on. Next, the substrate 11 is arranged on a flat stage 13, and a mold 14 in which a fine structure is formed is pressurized from above to contact the resin. As a pressurizing method, a method of pressing the mold by a flat tool 15 is in common use. Then, UV irradiation is performed by a UV irradiator 16 from above the mold 14 and the flat tool 15 to thereby cure the UV curing resin 12. Lastly, the mold 14 is released from the UV curing resin 12 by moving the flat tool 15 and the mold 14 upward.
However, as a direction of releasing the mold is a vertical direction with respect to a transfer plane in the above method, a large mold-release resistance is generated between the mold 14 and the cured UV curing resin 12. Accordingly, there is a problem that film peeling occurs between the UV curing resin 12 and the substrate 11 at the time of releasing the mold 14 from the UV curing resin 12 and thus the transfer quality of the fine pattern is not stabilized.
Japanese Patent No. 5499306 (Patent Document 1) discloses an imprinting method in which a film-shaped mold 14 is peeled off and released by lifting mold holding tools 17 arranged in end portions after the transfer as shown in FIG. 14. As the mold is released by peeling, not releasing the mold in the vertical direction with respect to the transfer plane, the mold-release resistance can be reduced and the transfer quality of the fine pattern can be stabilized. JP-A-2014-54735 (Patent Document 2) discloses an imprinting method in which the film-shaped mold 14 is peeled off and released by moving the mold 14 in the left direction in the drawing while pressing the mold 14 by using a pressurizing roll 151 as a pressurizing means and lifting the mold holding tool 17 after the transfer as shown in FIG. 15. Also in this case, the mold-release resistance can be reduced and the transfer quality of the fine pattern can be stabilized.